[PiP on CD] Adjust dismiss target and PiP menu sizes

for the current display, by updating the context before getting the UI
element sizes.

Recall: http://recall/clips/b60ddb55-6540-45b7-b535-46a86c461df3

Bug: 407139731
Test: atest PhoneSizeSpecSourceTest PipBoundsAlgorithmTest
PipBoundsStateTest PipTaskOrganizerTest PipResizeGestureHandlerTest
PipTouchHandlerTest TvPipGravityTest
Test: Manual - check that PiP menu action buttons and the dismiss target
is updated to a proportionally appropriate size when PiP is on external
display, as well as on primary display
Flag: com.android.window.flags.enable_connected_displays_pip

Change-Id: I62b546a9be96bb42df5e34380f7e2df7cbed52c5